Underground tanks are used to store large amounts of fluids such as water, gas, oil or solvents. These tanks must be anchored underground to prevent them from possibly floating upward or displacing due to ground water or moving. Conventional anchor blocks, also referred as deadman anchors, are made of concrete and underground tanks may be composed of steel, stainless steel, single, double, triple-wall fiberglass or a combination thereof.
Regulations in underground tank storing are rigorous because a failure in the installation or operation of the tank can lead to contamination of soil and groundwater or increased safety risks for workers during installation. For instance, workers may not be allowed to go inside the hole to the level of the anchor blocks beneath the tank and must stay at the top of the tank to perform installation or maintenance operations.
Generally, underground tanks are attached to concrete anchor blocks located on both sides of the tank, using anchor straps provided with hooks at either end. Known hooks may be classified under various categories such as C-shaped hooks, D-shaped hooks and T-shaped hooks. A hook is connected to each of the two ends of the strap and is configured to engage an anchor block provided below or at the bottom of the tank (as seen in FIGS. 1A and 1B). Straps may include fiberglass, nylon, polyester, steel or other adequate metallic materials.
To install underground tanks, several workers often throw an end of a strap from the top of the tank toward one of the anchor blocks so as to hook onto an anchor element of the anchor block. Workers have to repeat the throwing until they succeed in grabbing the concrete anchor with the hook. This operation is difficult because one end of the strap may be unhooked due to slack on the strap while workers are hooking or installing the other end of the strap. This operation is also difficult because the top of the tank is narrow and may be slippery for the workers. When workers are allowed to anchor the underground tank from the ground, one hooked end of the strap is generally maintained with difficulty on one anchor while workers hook the other end of the strap to the opposed anchor.
Furthermore, fluctuations of the water level or earth movements may lead to an undesirable unhooking from the anchor element.
As underground ambient conditions are favorable to rust and corrosion, materials and construction have to be chosen carefully. Stainless steel, fiberglass and hot dip galvanized cast iron are better suited for these rigorous conditions.
Known springhooks or hooks provided with a retaining mechanism, i.e. which opens and closes the hook opening under the action of a spring, have the challenge that moving mechanical components such as springs, often made of steel, may have a propensity to rust or corrode in certain environments. Additionally, the retention mechanism of the springhook is fragile.
There is indeed a need in the industry for a hook that would overcome at least some of the aforementioned disadvantages and challenges.